For many years file cabinet manufacturers have installed various devices known as interlock or anti-tip devices in file cabinets. Thus, when one file cabinet drawer is opened, the remainder of the file cabinet drawers are locked and cannot be opened until the first drawer has been returned to a closed position.
Most of these devices installed to one side of the cabinet employ some sort of projection which extends perpendicularly from the side of the drawer. When the drawer is opened, the projection on the drawer triggers a series of levers and cams which tend to jam, in one way or another, the other drawer mechanisms, preventing the associated drawers from opening.
Most commonly, a frame with a vertically aligned U-shaped channel is mounted on the inside of the cabinet and a plurality of vertically aligned locking bars move upwardly or downwardly when one of the drawers is activated. A cam or lever is usually mounted on one of the locking bars or on the side of the vertical channel. Such a device is found in U.S. Pat. No. 3,900,236, issued Aug. 19, 1975 to Goulish.
A more recent type of device is found in U.S. Pat. No. 4,936,640, invented by Isy S. Pratzer, which issued on Jun. 26, 1990 for ANTI-TIP MECHANISM AND METHOD PROVIDING ANTI-TIP DEVICE.
Still other anti-tip devices employ a series of linked cams which pivotally connect to adjacent cams on the adjacent drawer system. Such a device is found in U.S. Pat. No. 4,429,930.
Another method of accomplishing the same task is to employ elongate rods vertically mounted on the side of the cabinet with cam members fixed for simultaneous rotation on the rod. When a drawer is opened, the remainder of the drawers are prevented from moving past their respective cams. One of these older types of devices is found in U.S. Pat. No. 3,881,793--Anderson.
Although many of the new anti-tip devices function extremely well, and are very dependable, two problems still exist in the art. One is the complexity of the devices, i.e. the number of moving parts necessary for operation. A more serious drawback however is the wasted space necessary to house the devices in the cabinet. Obviously the addition of vertical tracks, frames, sliding bars, perpendicular protrusions, and other components necessitate a much larger cabinet than is needed to house the drawer slides and the drawers alone. This is an important consideration since space is a key factor in most offices.
Moreover, none of the present interlock devices incorporate an anti-rebound means. Anyone who has quickly closed a file cabinet drawer knows the problems associated with the drawers banging into the rear of the cabinet and then rebounding outwardly. If one drawer is closed while another is opened, simultaneously, the rebound of the second drawer could cause the interlock or anti-tip mechanism to malfunction. Thus, it is an added benefit to incorporate an anti-rebound device within an interlock system.
It is therefore an object of the present invention to create a combination improved interlock anti-tip and security locking device which is capable of functioning within the same space as is defined by the two or three channelled drawer slides installed to left-hand or right-hand side within the cabinet.